Radon gas mitigation systems and apparatus

ABSTRACT

A building panel may be installed below a slab in the construction of buildings. The building panel supports the slab and also provides a ventilation layer that may be depressurized to eliminate or reduce infiltration of radon gas into the building. The ventilation layer may comprise channels which provide a two-dimensionally interconnected void. Ventilation panels which include collars for connecting to ventilation systems may be provided. The panels may be installed directly on compacted soil. The building panels may additionally provide sub-slab insulation and/or a capillary break for water drainage. In some embodiments the building panels are formed substantially entirely of thermal insulating material such as rigid polystyrene foam. In an example embodiment the panels are approximately 4 inches thick and have a grid of intersecting channels formed on an underside of the panels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International Application No.PCT/CA2014/050198 filed 7 Mar. 2014, which claims priority from U.S.Application No. 61/775,203 filed 8 Mar. 2013. For purposes of the UnitedStates, this application claims the benefit under 35 U.S.C. §119 of U.S.Application No. 61/775,203 filed 8 Mar. 2013, and entitled COMBINEDSUB-SLAB RADON GAS MITIGATION & INSULATION PANELS which is herebyincorporated herein by reference for all purposes.

TECHNICAL FIELD

The invention relates to buildings and more specifically to systems andapparatus for preventing radon gas from accumulating in buildings.

BACKGROUND

Radon is a naturally-occurring radioactive gas created from the decay ofuranium, which is found in rock, soil and water. When radon is createdit normally dissipates into the atmosphere. However, buildings can trapradon where it can become concentrated enough to be a health hazard.

Different countries have different guidelines relating to the managementof radon. Health Canada's guidelines provide that remedial measuresshould be undertaken in a dwelling whenever the average annual radonconcentration exceeds 200 becquerels per cubic meter (200 Bq/m³) in thenormal occupancy area. The US Environmental protection Agency guidelinesfor maximum exposure are 150 becquerels per cubic meter (150 Bq/m³).

Both the Canadian National Building Code and the US InternationalBuilding Code have Radon mitigation requirements. Health Canadarecommends that the construction of new dwellings should employtechniques that will minimize radon entry and will facilitatepost-construction radon removal, should this subsequently provenecessary. One radon reduction method is Active Soil Depressurisation(ASD). ASD involves inserting a pipe through a hole drilled through abasement floor. A fan draws the radon gas from under the floor andpushes it outside.

A radon ventilation system (RVS) can be provided in new construction toprevent buildings from trapping radon. A RVS may be used in homes,apartments or other buildings. A RVS may be made by placing a layer ofcoarse gravel or perforated pipes underneath the basement slab andwithdrawing air from the layer of coarse gravel or perforated pipes.

There are issues with using gravel to create an under-slab airflowlayer. Gravel may be in limited supply or prohibitively expensive in theregion where the building is being constructed. A gravel layer may notwork depending on the gravel supply and installation procedure. Gravelmay itself release radon gas. Relying on perforated piping to removeradon is prone to failure as radon may not migrate into the piping.

There is a need for effective, reliable and affordable systems forpreventing the buildup of radon gas in dwellings and other buildings.

SUMMARY

This invention has a number of aspects. One aspect provides systems forradon mitigation. Another aspect provides apparatus which may be used ascomponents of such systems. The present disclosure provides severalembodiments, including the following:

Embodiment 1 provides a ventilation panel comprising a generally planarbody having first and second opposed surfaces and a ventilation layer onthe second surface of the body. The ventilation layer provides atwo-dimensionally interconnected void and the ventilation panel has aload-bearing capacity in a transverse direction of at least 150 poundsper square foot (about 4.8 kPa).

Embodiment 2 provides a ventilation panel according to embodiment 1wherein the ventilation layer comprises a plurality of support padsprojecting from the second surface, the support pads spaced apart fromone another to provide the interconnected void.

Embodiment 3 provides a ventilation panel according to embodiment 1wherein the body comprises a thermally-insulating material.

Embodiment 4 provides a ventilation panel according to embodiment 3wherein the thermally insulating material comprises a rigid foam.

Embodiment 5 provides a ventilation panel according to embodiment 4wherein the rigid foam comprises polystyrene.

Embodiment 6 provides a ventilation panel according to any one ofembodiments 3 to 5 wherein the ventilation layer comprises a pluralityof support pads projecting from the second surface, the support padsspaced apart from one another to provide the interconnected void.

Embodiment 7 provides a ventilation panel according to embodiment 6wherein the support pads are formed of the thermally insulatingmaterial.

Embodiment 8 provides a ventilation panel according to embodiment 7wherein the support pads are integral with the body.

Embodiment 9 provides a ventilation panel according to any one ofembodiments 1 through 7 wherein the interconnected void is provided by aplurality of interconnected channels.

Embodiment 10 provides a ventilation panel according to embodiment 9wherein the channels have widths narrower than 3 inches.

Embodiment 11 provides a ventilation panel according to any one ofembodiments 9 and 10 wherein the channels have widths exceedingone-eighth inch.

Embodiment 12 provides a ventilation panel according to any one ofembodiments 9 to 11 wherein the channels comprise a first set ofparallel channels arranged to intersect with channels of a second set ofparallel channels.

Embodiment 13 provides a ventilation panel according to any one ofembodiments 1 to 12 wherein the first and second surfaces are spacedapart from one another by a distance of 6 inches or less.

Embodiment 14 provides a ventilation panel according to any one ofembodiments 2 and 6 wherein the support pads each have a length shorterthan 2 inches.

Embodiment 15 provides a ventilation panel according to any one ofembodiments 2, 6, and 14 wherein the support pads have a length longerthan ½ inch.

Embodiment 16 provides a ventilation panel according to any one ofembodiments 2, 6, 14, and 15 wherein the support pads are spaced apartfrom one another in an array such that adjacent ones of the support padsare spaced apart by distances of 3 inches or less.

Embodiment 17 provides a ventilation panel according to any one ofembodiments 2, 6, and 14 to 16 wherein adjacent ones of the support padsare spaced apart from one another by distances greater than one-eighthinch.

Embodiment 18 provides a ventilation panel according to any one ofembodiments 2, 6, and 14 to 17 wherein the support pads comprise prisms,trapezoids, cubes or conical forms.

Embodiment 19 provides a ventilation panel according to any one ofembodiments 1 to 18, wherein the insulating body and the ventilationlayer are made from different materials.

Embodiment 20 provides a ventilation panel according to embodiment 19,wherein the ventilation layer comprises one or more of nylon, vinyl,polyvinyl chloride.

Embodiment 21 provides a ventilation panel as defined in any one ofembodiments 19 and 20, wherein the ventilation layer comprises non-wovennylon or rock wool.

Embodiment 22 provides a ventilation panel according to any one ofembodiments 1 to 21 wherein the volume of the interconnected voidrelative to the volume of the supporting pads is at between 5% to 80%.

Embodiment 23 provides a ventilation panel according to any one ofembodiments 1 to 22 wherein the interconnected void has a volume that isat least 20% of a volume of the ventilation layer.

Embodiment 24 provides a ventilation panel according to any one ofembodiments 1 to 23 wherein the interconnected void has a volume of atleast 1¼ cubic inches per square foot of the panel.

Embodiment 25 provides a ventilation panel according to any one ofembodiments 1 to 24 wherein the panel has an insulating value of atleast R8.

Embodiment 26 provides a ventilation panel according to embodiment 25wherein the panel has an insulating value of R6 to R14.

Embodiment 27 provides a ventilation panel according to any one ofembodiments 1 to 26 comprising at least one knockout configured to beremovable to provide a ventilation opening through the body and into theinterconnected void.

Embodiment 28 provides a ventilation panel according to any one ofembodiments 1 to 27 comprising an aperture extending through the body tothe interconnected void and a collar sealed to the aperture, the collarcomprising a fitting on the first side of the body, the fittingconfigured for coupling to a ventilation conduit.

Embodiment 29 provides a building construction comprising a panelaccording to any one of embodiments 1 to 28 arranged with theventilation layer beneath the body, a concrete slab poured on top of thepanel, and a ventilation system connected to withdraw air from theinterconnected void.

Embodiment 30 provides a building construction according to embodiment29 wherein the panel comprises an aperture, and the ventilation systemcomprises a collar fitting extending through the concrete slab andconnected to draw air through the aperture.

Embodiment 31 provides a building construction according to embodiment30 comprising an exhaust pipe inserted through the collar fitting.

Embodiment 32 provides a building construction according to embodiment31 wherein the exhaust pipe comprises a ventilation stack extending to avent located outside the building.

Embodiment 33 provides a building construction according to any one ofembodiments 29 to 32 comprising an impervious barrier between the paneland the concrete slab.

Embodiment 34 provides a building construction as defined in embodiment33, wherein the impervious barrier comprises a polyethylene barrier.

Embodiment 35 provides a building construction as defined in any one ofembodiments 31 and 32, further comprising a fan operatively connected tothe exhaust pipe wherein the fan actively removes gases from theinterconnected void.

Embodiment 36 provides a building construction as defined in any one ofembodiments 30 to 32 and 35, comprising a sump pit located under theaperture.

Embodiment 37 provides a ventilation panel comprising a generally planarbody of a closed cell foam material having first and second opposedsurfaces and a ventilation layer on the second surface of the body. Theventilation layer provides a two-dimensionally interconnected void.

Embodiment 38 provides a ventilation panel according to embodiment 37wherein the ventilation layer comprises a plurality of support padsprojecting from the second surface, the support pads spaced apart fromone another to provide the interconnected void.

Embodiment 39 provides a ventilation panel according to embodiment 38wherein the support pads are formed of the closed cell foam material.

Embodiment 40 provides a ventilation panel according to any one ofembodiments 38 and 39 wherein the support pads are formed integrallywith the body.

Embodiment 41 provides a ventilation panel according to any one ofembodiments 37 to 40 wherein the closed cell foam material comprises apolystyrene foam.

Embodiment 42 provides a ventilation panel according to any one ofembodiments 37 to 41 wherein the interconnected void is provided by aplurality of interconnected channels.

Embodiment 43 provides a ventilation panel according to embodiment 42wherein the channels comprise first and second sets of set ofintersecting channels

Embodiment 44 provides a ventilation panel according to embodiment 43wherein the channels of the first set of channels are parallel to oneanother and the channels of the second set of channels are parallel toone another.

Embodiment 45 provides a ventilation panel according to any one ofembodiments 42 to 44 wherein the channels have widths narrower than 3inches.

Embodiment 46 provides a ventilation panel according to any one ofembodiments 42 to 45 wherein the channels have widths exceedingone-eighth inch.

Embodiment 47 provides a ventilation panel according to any one ofembodiments 37 to 46 wherein the first and second surfaces are spacedapart from one another by a distance of 6 inches or less.

Embodiment 48 provides a ventilation panel according to any one ofembodiments 37 to 47 wherein the volume of the interconnected voidrelative to the volume of the supporting pads is in the range of 5% to80%.

Embodiment 49 provides a ventilation panel according to any one ofembodiments 37 to 48 wherein the interconnected void has a volume thatis at least 20% of a volume of the ventilation layer.

Embodiment 50 provides a ventilation panel according to any one ofembodiments 37 to 49 wherein the interconnected void has a volume of atleast 1¼ cubic inches per square foot of the panel.

Embodiment 51 provides a ventilation panel according to any one ofembodiments 37 to 50 wherein the panel has an insulating value of atleast R8.

Embodiment 52 provides a ventilation panel according to embodiment 51wherein the panel has an insulating value of R6 to R14.

Embodiment 53 provides a ventilation panel according to any one ofembodiments 37 to 52 comprising at least one knockout configured to beremovable to provide a ventilation opening through the body and into theinterconnected void.

Embodiment 54 provides a ventilation panel according to any one ofembodiments 37 to 53 comprising an aperture extending through the bodyto the interconnected void and a collar sealed to the aperture, thecollar comprising a fitting on the first side of the body, the fittingconfigured for coupling to a ventilation conduit.

Embodiment 55 provides a ventilation panel according to any one ofembodiments 37 to 54, wherein the insulating body and the ventilationlayer are made from different materials.

Embodiment 56 provides a ventilation panel according to any one ofembodiments 37 to 55, wherein the ventilation layer comprises one ormore of nylon, vinyl, polyvinyl chloride.

Embodiment 57 provides a ventilation panel as defined in any one ofembodiments 37 to 56, wherein the ventilation layer comprises non-wovennylon or rock wool.

Embodiment 58 provides a building construction comprising a panelaccording to any one of embodiments 37 to 57 arranged with theventilation layer beneath the body, a concrete slab on top of the panel,and a ventilation system connected to withdraw air from theinterconnected void.

Embodiment 59 provides a building construction according to embodiment58 wherein the panel comprises an aperture, and the ventilation systemcomprises a collar fitting extending through the concrete slab andconnected to permit air to flow through the aperture.

Embodiment 60 provides a building construction according to embodiment59 further comprising an exhaust pipe coupled to the collar fitting.

Embodiment 61 provides a building construction according to embodiment60 wherein the exhaust pipe comprises a ventilation stack extendingoutside the building.

Embodiment 62 provides a building construction according to any one ofembodiments 58 to 61 comprising an impervious barrier between the paneland the concrete slab.

Embodiment 63 provides a building construction according to embodiment62, wherein the impervious barrier comprises a polyethylene barrier.

Embodiment 64 provides a building construction according to any one ofembodiments 59 to 63 comprising a fan operatively connected to draw airfrom the interconnected void through the aperture.

Embodiment 65 provides a building construction as defined in any one ofembodiments 59 to 64, comprising a sump pit located under the aperture.

Further aspects and example embodiments are illustrated in theaccompanying drawings and/or described in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate non-limiting example embodiments ofthe invention.

FIG. 1 shows an example radon ventilation system in a building.

FIG. 1A shows a partially schematic detailed view of a construction thatincludes a panel underlying and supporting a slab.

FIG. 2 is a top plan view of an example sub-slab ventilation panel.

FIG. 3 is a bottom plan view of the FIG. 2 panel.

FIG. 3A is a magnified view of a section of FIG. 3.

FIG. 4 is a side elevation view of the FIG. 2 panel.

FIG. 4A is an expanded cross-sectional view of a panel showing anexample channel profile.

FIG. 5A is a bottom elevation view of an example insulating ventilationpanel showing having prismatic support pads.

FIG. 5B is a bottom elevation view of an example insulating ventilationpanel having trapezoidal support pads.

FIG. 5C is a bottom elevation view of an example insulating ventilationpanel having cube-like support pads.

FIG. 5D is a bottom elevation view of a further example insulatingventilation panel having a supporting air permeable layer beneath aninsulating body.

FIG. 6 is a top elevation view of an embodiment of the insulatingventilation panel showing a vent conduit.

FIG. 7 is a top elevation view of an embodiment of the insulatingventilation panel showing a plurality of vent knockouts.

FIG. 8 is a top elevation view of an embodiment of the insulatingventilation panel showing a collar fitting.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Throughout the following description, specific details are set forth inorder to provide a more thorough understanding of the invention.However, the invention may be practiced without these particulars. Inother instances, well known elements have not been shown or described indetail to avoid unnecessarily obscuring the invention. Accordingly, thespecification and drawings are to be regarded in an illustrative, ratherthan a restrictive sense.

FIG. 1 depicts building 10 having a basement area 12. Basement area 12comprises foundation walls 14, 16 and basement slab 18. If building 10is in an area where radon is present, radon gas from the soil under andsurrounding building 10 may infiltrate into basement area 12 and maysubsequently accumulate to unhealthy levels in building 10, especiallyin basement area 12.

Building 10 has a radon ventilation system 20. Radon ventilation system20 comprises panels 21 that underlie slab 18. Panels 21 support slab 18and provide an airflow layer 24 under slab 18. Panels 21 also optionallybut advantageously provide thermal insulation on the underside of slab18. In the illustrated embodiment, panels 21 provide an insulation layer22 between slab 18 and airflow layer 24. Thus, in the illustratedembodiment, panels 21 provide a supporting substrate for slab 18,provide thermal insulation under slab 18 and also provide an airflowlayer which permits depressurization under slab 18 to prevent the entryof radon into building 10 from the underlying soil. The airflow layermay also optionally but advantageously function as a capillary break todissipate groundwater pressure and facilitate its drainage. A waterdrainage system not shown may be provided to withdraw any water thatenters airflow layer 24.

Airflow layer 24 permits air containing radon gas to travel freely intwo dimensions under slab 18. One or more vent conduits 26 are coupledto airflow layer 24 and provide routes to draw air containing radon gasthrough vent conduit 26 into vent stack 28 to exit building 10 throughexhaust point 30. The flow of air from airflow layer 24 through ventstack 28 may be driven passively. For example, air carrying radon gasmay be caused to flow by a natural stack effect created by thepositioning of vent stack 28 and exhaust point 30. In addition or in thealternative, the flow of air from airflow layer 24 out vent stack 28 maybe actively driven, for example, a fan 29 in vent conduit 26 may exhaustair from airflow layer 24. Some embodiments provide activedepressurization wherein air is withdrawn from airflow layer 24 at arate such that an air pressure within airflow layer 24 is lower than anair pressure in basement 12.

In the illustrated embodiment, panels 21 are also provided on outsidesof foundation walls 14, 16 below grade. Panels 21 provide insulation andadditionally provide airflow passages from which radon gas can bediverted before it enters building 10. Vertical panels 21 arrangedaround the outside of a foundation may be arranged to provide an airflowlayer that vents passively at the upper edges of panels 21 to allowradon to dissipate into the atmosphere. The airflow layer of verticalpanels 21 may additionally provide a capillary break to dissipategroundwater pressure and facilitate its drainage. A perimeter drainagesystem may be arranged below the lower edges of vertical panels 21 todrain water from the airflow layer provided by vertical panels 21.

A sump pit 32 may optionally be provided below vent conduit 26 toprevent blockage of vent conduit 26 by water or other materials. Otherunder-slab drainage may optionally be provided.

FIG. 1A is a partially schematic detailed view of a construction thatincludes a panel 21 underlying and supporting a slab 18. This embodimentincludes an impervious barrier 33 between panels 21 and slab 18. Theimpervious barrier may, for example, comprise a membrane such as apolyethylene sheet. In a typical application, barrier 33 may comprise a6 mm thick polyethylene barrier lapped and sealed between insulationlayer 22 and slab 18.

FIGS. 2-4 depict an example sub-slab panel 100 that may be used as apanel 21. Panel 100 provides an airflow layer 24 which is made up by aplurality of support pads 104 that are defined between airflow channels105 which collectively provide an interconnected void 106.Interconnected void 106 is configured such that airflow between twopoints in void 106 can occur through multiple paths. Thus, isolatedblockages of one or more channels 105 are unlikely to prevent air fromreaching a vent conduit 26 (not shown). In the embodiments illustratedin FIGS. 2 to 4, channels 105 include a first set of channels 105A thatintersect with channels 105B of a second set of channels.

A panel may have any suitable size. In some non-limiting embodiments,panels like panel 100 or any other embodiment is rectangular and hassides in the range of 1 to 12 feet in length. For example, panels asdescribed herein may have dimensions of 4 feet by eight feet for someapplications. It is convenient but not mandatory for panels as describedherein to have overall length and width dimensions that are multiples ofa basic unit used in construction such as multiples of 6 or 12 inchesfor construction based on imperial measurements or multiples of 10, 20,50 or 100 centimeters for construction based on metric measurements.

In the illustrated embodiment channels 105 terminate at spaced-apartlocations along each side of panel 100 such that two or more panels 100may be abutted to provide a continuous airflow layer. While it is notmandatory, it is convenient for channels 105A to be parallel to oneanother and to make channels 105B parallel to one another. In suchembodiments, support pads may be square, rectangular orparallelogram-shaped. In one embodiment as shown, for example, in FIGS.3 and 3A, interconnected void 106 is formed by crossing perpendicularchannels 105A and 105B. Channels 105A, 105B may, for example, form awaffle or grid pattern to an appropriate depth over the entire surfaceof panel 100. Support pads of other shapes may be provided inalternative embodiments. For example, support pads may be round,oval-shaped, triangular, etc.

A wide range of other configurations for the channels are possible. Forexample, channels 105 could radiate outwardly from one or more nodes,channels 105 could follow curving paths etc. Where channels 105 includechannels that are parallel to one another it is not mandatory that thechannels run parallel to edges of the panel. For example, the channelscould run at a non-parallel, non-perpendicular angle to an edge of thepanel. The channels could, for example, run at an angle in the range of15 to 75 degrees to an edge of the panel. In embodiments where the panelcomprises sets of intersecting channels there could be two or more setsof intersecting channels. For example some embodiments may have threesets of intersecting channels. The three sets of intersecting channelsmay define support pads that have triangular shapes.

In some embodiments the insulating layer of panel 100 (or other layersupporting support pads 104) projects outwardly past support pads 104along the peripheral edges of the panel 100 such that void 106 can becontinuous between abutting panels 100 even if channels 105 on one panel100 are not aligned with corresponding channels 105 on the abuttingpanel 100.

FIG. 3A is a magnified view of a section of the panel 100 of FIG. 3depicting support pads 104, interconnected void 106, and channels 105A,105B. The dimensions indicated in FIG. 3A are illustrative only and maybe varied. FIG. 4 is a side elevation view of panel 100.

The widths, depths and cross-sectional shapes of channels 105 may bevaried. In some embodiments, channels 105 have cross-sectional areassuch that the total volume of interconnected void 106 is in the range of20% to 80% of the volume of the layer containing channels 105. In someembodiments, the total volume of interconnected void 106 occupies morethan 20% or 30% of the volume of the layer containing channels 105. Thelayer containing channels 105 may have a total volume equal to an areaof the panel multiplied by the depth of channels 105. In someembodiments the interconnected void has a volume of at least 1¼ cubicinches per square foot of the panel.

The widths and depths of channels 105 may be chosen based on variousfactors including:

-   -   achieving a desired volume for void 106;    -   maintaining an area of support pads 104 sufficient to support        slab 18 and its designed loading with a suitable safety factor;    -   maintaining a desired insulation value;    -   providing a panel that is strong enough to maintain its        integrity in reasonable handling prior to installation and        during pouring of slab 18; and    -   achieving a free flow of air through void 106.        Some of these design factors will depend on the properties of        the material from which panel 100 is made and/or on the overall        thickness of panel 100. For specific applications a panel may be        custom-engineered. Factors such as the width of channels, the        area of bearing surfaces (e.g. support pads) the depths of        channels, the properties of the material of which the panel is        made and the like may be determined based on design parameters        such as one or more of: the required load bearing capacity, the        properties of underlying soil, the usage of the building, the        rate at which radon is produced at the location of the building,        etc.

In an example embodiment, panel 100 has an overall thickness of 4 inches(about 10 cm) and channels 105 have a depth of about 1 inch (about 2½cm). Channels 105 may, for example, have depths in the range of about ⅜inch to about 2 inches. In some embodiments, channels 105 penetrate inthe range of about 1/10 to about ½ of the overall thickness of panel100.

Making channels 105 not too wide, e.g. less than 3 inches or so, cantend to make panel 100 better able to withstand handling duringinstallation and pouring of slab 18. In some embodiments, channels 105have widths in the range of about ⅛ inch (about ¼ cm) to about 3 inches(about 7½ cm). In an example embodiment (see e.g. FIG. 5C) channels105A-C, 105B-C have widths W_(C) of about 2 inches. It is not mandatorythat all of channels 105 have the same widths or that the width of anyone channel 105 remain constant along its length.

Forming channels 105 to have cross-sectional shapes such that thecorners formed at the intersections of channels 105 and the surface ofpanel 100 are curved rather than sharp can be advantageous in enhancingair flow, reducing noise from air flow, preserving the appearance ofpanel 100 during handling and/or reducing the likelihood that smallchunks of the material of panel 100 could break off during installation.FIG. 4A is an expanded cross-sectional view through a set of channels105 which have a rounded cross-sectional profile.

Channels 105 may have smooth walls to facilitate airflow. Such smoothwalls may, for example, be formed by extrusion, hot-wire cutting etc.

The dimensions of support pads 104 may vary. Where a panel 100 isdesigned to support a certain loading each area of the panel should haveenough support pads 104 with a sufficient area to support the desiredloading without exceeding a bearing capacity of the soil and withoutexceeding the strength of the material of support pads 104. In manycases this is not overly limiting since properly compacted soil at abuilding site will typically have a maximum loading well in excess ofthe loading specified for a basement floor. For example, for someapplications a panel 100 may be designed to support a loading of about300-600 lb/sq feet when installed on compacted soil that can support aloading of, for example, 3000 pounds per square foot. In someembodiments panels as described in any of the example embodiments hereinprovide a load-bearing capacity in a transverse direction of at least150 pounds per square foot (about 4.8 kPa)

As shown in FIG. 4 an example embodiment of a panel has support pads 104which have a thickness dimension T₁ of about ½ inch to 2 inches(corresponding to channels of a depth T₁. FIG. 3A shows example supportpads 104 which have a width dimension W and a length dimension L ofabout 2 inches.

Support pads 104 may be formed of the same material as the rest of panel100 or a different material. Physical properties of the material ofpanel 100 may be selected for compatibility with the conditions underslab 18, to provide desired load-carrying ability, and to provide otherdesired characteristics such as a desired insulating value. In someembodiments, panel 100 comprises a thermally-insulating material andsupport pads 104 are also made of the thermally-insulating material. Insome embodiments, panels 100 are made of closed-cell foam materials.Example materials from which panel 100 may be fabricated includethermally-insulating materials such as expanded polystyrene foam,extruded polystyrene foam, and soy foam. In some embodiments thematerial of panel 100 is a material, which may be a foam material,having a minimum compressive strength exceeding 10 psi (pounds persquare inch). In some embodiments the minimum compressive strength ofthe material of a panel 100 is at least 20, 30, 40 or 60 or more psi.

Panel 100 may be constructed to provide a desired insulating R-value.Considerations such as the environment or legislative requirements mayinfluence the desired R-value. A desired R-value may be achieved byvarying the thickness T₂ of a continuous layer 100A of panel 100 fromwhich support pads 104 project. In some embodiments, panels 100 providean R-value in the range of 6 to 20, for example an R-value of 12.

A panel 100 may be fabricated by any of a wide variety of methods. Inone method material is removed from a sheet of insulating material (e.g.by cutting) to form channels 105 in a crossing pattern to an appropriatedepth. In another example method, an insulating ventilation panel 100 ismade by extruding or casting an insulating foam material into a moldwhich is shaped to form channels 105. In another example method a panelis made by attaching support pads or a layer of material that has beenshaped to provide support pads or a layer of a material that otherwiseprovides an interconnected void is attached to an insulating panel.Another method may create a insulating ventilation panel 100 by firstextruding or casting or otherwise forming support pads 104 with materialsuch as nylon, vinyl, or polyvinyl chloride and then fastening supportpads 104 to the bottom of an insulating body 102.

In some embodiments, panels 100 have formed in them knockouts at one ormore locations for receiving vent conduits. An installer may remove aknockout at a location at which it is desired to install a vent conduitand then mate a vent conduit to the aperture so-formed in panel 100.FIG. 7 shows an example panel 300 comprising a plurality of exhaust ventknockouts 306. Exhaust vent knockouts 306 are removable sections of theinsulating body 302 and optionally removable sections of support pads304. An installer can select the location of a vent conduit by removingout one of the exhaust vent knockouts 306. Multiple vent conduits can becreated if desired by removing multiple exhaust vent knockouts 306. Asan alternative to using knockouts 306, an installer may cut a holethrough a panel 100 at a location desired for a vent using, for example,as suitably-sized hole saw, a hand saw, knife or the like. In someembodiments, a panel 100 includes markings to indicate suitablelocations for making vent openings through the panel.

In some embodiments, differently-configured venting panels are provided.Such venting panels may be supplied with a venting aperture pre-formed,one or more knockouts for venting apertures, or a venting conduitalready sealed in place. In such embodiments a venting panel may beplaced at location(s) at which it is desired to vent void 106.

In some embodiments the venting panels are smaller than other panels100. For example, panels 100 may be rectangular having a length longerthan a width. Venting panels for use with such panels 100 may have alongest dimension equal to the width of panels 100. Such venting panelsmay, for example, be square or rectangular. Various example ventingpanels are illustrated in FIGS. 5A through 5D.

The example venting panels of FIGS. 5A through 5D have variousalternative arrangements of channels and support pads. Regular panels100 may also use such arrangements of channels and support pads. FIGS.5A, 5B, and 5C show example insulating ventilation panels 100A, 100B,and 100C, respectively. The airflow layer of insulating ventilationpanels 100A, 100B, and 100C are similar to panel 100 except that supportpads 104A, 104B and 104C have different forms and dimensions. Thefigures depict that support pads 104 may be shaped as prisms 104A,trapezoids 104B or cubes 104C. In other example embodiments, supportpads comprise truncated conical forms

FIG. 5D depicts a further embodiment of the insulating ventilation panel100D. In this embodiment, panel 100D comprise an insulating body 102D(such as a sheet of a rigid insulation) and an air permeable layer 104D.Insulating body 102D and air permeable layer 104D may be fastenedtogether in any suitable manner. Air permeable layer 104D may be made ofmaterial such as non-woven nylon, rock wool or other similar breathablematerial capable of supporting the expected loads plus an appropriatesafety factor while allowing relatively unrestricted airflow.

A panel as illustrated in FIG. 5A may be made, for example, by millingor sawing channels 105 to provide support pads 104A between thechannels. A panel as illustrated in FIG. 5B may be made, for example asa composite in which support pads 104B are made of a different materialthan the body of the panel. For example, the support pads may be made ofPVC or nylon or vinyl while the body is made of a closed-cell foam. Apanel as illustrated in FIG. 5C may be made, for example, by moulding orcasting. A panel as shown in FIG. 5D may be made, for example, byattaching the ventilation layer to the body. These examples offabrication methods are non-limiting examples only.

FIG. 6 depicts an example insulating ventilation panel 200 comprising aninsulating body 202 and support pads 204. In addition, insulatingventilation panel 200 has vent conduit 206. Vent conduit 206 extendsthrough insulating body 202. In some embodiments support pads 204adjacent to vent conduit 206 may be absent to permit greater airflow anddecreased chances vent conduit 206 is blocked. In other embodiments,there may be more than one vent conduit 206. Additional vent conduitsallow radon-containing air to be vented vent from multiple exits.

FIG. 8 shows an example insulating ventilation panel 400. A collarfitting 408 is connected to vent conduit 406. Collar fitting 408 can bemounted on the top or bottom of vent conduit 406. In some embodiments ofinsulating ventilation panel 400, collar fitting 408 is cast into ventconduit 406. Collar fitting 408 can be, for example made of ABS, PVC,plastic or metal and may be configured to be coupled to conventionalplumbing or venting piping. In some embodiments support pads 404 areprovided.

Panels 100 may be used in construction by preparing a layer of compactedsoil to receive a slab. The soil may be as-found at the building site,gravel, or the like. It is not required that the soil have any specificpermeability to air since a highly-permeable two-dimensionallyinterconnected void is provided by the panels themselves. Any desiredsub-slab features such as sumps, sub-slab water-drainage etc. may beinstalled at this stage. After this has been done, panels 100 may belaid directly on the soil with the air-permeable layer down and supportpads (if the embodiment of panels being used has support pads) incontact with the soil. Panels 100 are installed abutting against oneanother such that their airflow layers provide a continuoustwo-dimensionally connected void between panels 100 and the underlyingsoil. Panels 100 may be cut to fit the area of the proposed slab. One ormore vent openings connected to the interconnected void are provided.This may be done by any one or more of: cutting a hole of a desired sizein a panel 100 at the location of a desired vent opening and installinga collar to interface to the hole; removing a pre-formed knockout at thedesired location and installing a collar to interface to the resultinghole; placing a venting panel having a pre-installed collar at thedesired vent location etc.

A barrier layer is provided on top of the panels. In some embodimentsthe panels are sufficiently impermeable that a barrier layer may beprovided by sealing strips of a suitable material along the jointsbetween abutting panels 100. In some embodiments a barrier layer such asa polyethylene sheet is applied over panels 100 (suitably lapped andsealed at any joints). After the barrier layer has been applied aconcrete slab may be poured. The venting collar(s) may be connected tosuitable ventilation systems.

Panels as described herein are not limited to application under slabs.Such panels may also be used under foundations (as long as they aredesigned to support the required foundation loading which will often belarger than the loading required for under-slab materials). Such panelsmay also be used in place of ordinary insulation panels.

INTERPRETATION OF TERMS

Unless the context clearly requires otherwise, throughout thedescription and the

-   -   “comprise”, “comprising”, and the like are to be construed in an        inclusive sense, as opposed to an exclusive or exhaustive sense;        that is to say, in the sense of “including, but not limited to”;    -   “or”, in reference to a list of two or more items, covers all of        the following interpretations of the word: any of the items in        the list, all of the items in the list, and any combination of        the items in the list;    -   the singular forms “a”, “an”, and “the” also include the meaning        of any appropriate plural forms.

Words that indicate directions such as “vertical”, “transverse”,“horizontal”, “upward”, “downward”, “forward”, “backward”, “inward”,“outward”, “vertical”, “transverse”, “left”, “right”, “front”, “back”,“top”, “bottom”, “below”, “above”, “under”, and the like, used in thisdescription and any accompanying claims (where present), depend on thespecific orientation of the apparatus described and illustrated. Thesubject matter described herein may assume various alternativeorientations. Accordingly, these directional terms are not strictlydefined and should not be interpreted narrowly.

Specific examples of systems, methods and apparatus have been describedherein for purposes of illustration. These are only examples. Thetechnology provided herein can be applied to systems other than theexample systems described above. Many alterations, modifications,additions, omissions, and permutations are possible within the practiceof this invention. This invention includes variations on describedembodiments that would be apparent to the skilled addressee, includingvariations obtained by: replacing features, elements and/or acts withequivalent features, elements and/or acts; mixing and matching offeatures, elements and/or acts from different embodiments; combiningfeatures, elements and/or acts from embodiments as described herein withfeatures, elements and/or acts of other technology; and/or omittingcombining features, elements and/or acts from described embodiments.

It is therefore intended that the following appended claims and claimshereafter introduced are interpreted to include all such modifications,permutations, additions, omissions, and sub-combinations as mayreasonably be inferred. The scope of the claims should not be limited bythe preferred embodiments set forth in the examples, but should be giventhe broadest interpretation consistent with the description as a whole.

What is claimed is:
 1. A building construction comprising: a ventilationpanel, the ventilation panel comprising: a generally planar body havingfirst and second opposed surfaces; and a ventilation layer on the secondsurface of the body, the ventilation layer providing a two-dimensionallyinterconnected void; the ventilation panel arranged with the ventilationlayer beneath the body; a concrete slab poured on top of and supportedby the ventilation panel; and a ventilation system connected to withdrawair from the interconnected void; wherein the body of the ventilationpanel supports a lowermost part of the concrete slab above an uppermostpart of the two-dimensionally interconnected void.
 2. A buildingconstruction according to claim 1 wherein the ventilation panel has aload-bearing capacity in a transverse direction of at least 150 poundsper square foot (about 4.8 kPa).
 3. A building construction according toclaim 1 wherein the ventilation panel comprises an aperture, and theventilation system comprises a collar fitting extending through theconcrete slab and connected to draw air through the aperture.
 4. Abuilding construction according to claim 3 comprising an exhaust pipeinserted into the collar fitting wherein the exhaust pipe comprises aventilation stack extending to a vent located outside the building.
 5. Abuilding construction according to claim 4 comprising a fan operativelyconnected to the exhaust pipe wherein the fan actively removes gasesfrom the interconnected void.
 6. A building construction according toclaim 3 comprising an impervious barrier between the panel and theconcrete slab wherein the impervious barrier comprises a polyethylenebarrier.
 7. A building construction according to claim 1, comprising asump pit located under the aperture.
 8. A building constructionaccording to claim 1 wherein the ventilation layer comprises a pluralityof support pads projecting from the second surface, the support padsspaced apart from one another to provide the interconnected void.
 9. Aventilation panel according to claim 8 wherein the body projectsoutwardly past the support pads along the peripheral edges of theventilation panel.
 10. A building construction according to claim 8wherein the support pads are integral with the body.
 11. A buildingconstruction according to claim 10 wherein the support pads compriseprisms, trapezoids, cubes or conical forms.
 12. A building constructionaccording to claim 8 wherein a volume of the interconnected voidrelative to a volume of the supporting pads is between 5% to 80%.
 13. Abuilding construction according to claim 12 wherein the thermallyinsulating material comprises a rigid foam.
 14. A building constructionaccording to claim 1 wherein the body comprises a thermally-insulatingmaterial.
 15. A building construction according to claim 1 wherein theinterconnected void is provided by a plurality of interconnectedchannels.
 16. A building construction according to claim 15 wherein thechannels have widths narrower than 3 inches.
 17. A building constructionaccording to claim 15 wherein the channels comprise a first set ofparallel channels arranged to intersect with channels of a second set ofparallel channels.
 18. A building construction according to claim 1,wherein the body and the ventilation layer are made from differentmaterials.
 19. A building construction according to claim 18, whereinthe ventilation layer comprises one or more of nylon, vinyl, polyvinylchloride.
 20. A building construction according to claim 18, wherein theventilation layer comprises non-woven nylon or rock wool.
 21. A buildingconstruction according to claim 1 wherein the building construction withone another to provide a continuous airflow layer under the slab, eachof the additional ventilation panels comprising: a generally planar bodyhaving first and second opposed surfaces; and a ventilation layer on thesecond surface of the body, the ventilation layer comprising a pluralityof support pads projecting from the second surface to provide atwo-dimensionally interconnected void wherein the support pads arespaced apart from one another to provide the interconnected void.
 22. Abuilding construction according to claim 21 wherein the body of theadditional ventilation panels projects outwardly past the support padsalong the peripheral edges of the additional ventilation panels toprovide channels in the ventilation layers along abutting edges of theadditional ventilation panels.
 23. A building construction according toclaim 1 comprising additional ventilation panels on an outside of afoundation below grade, the additional ventilation panels arrangedaround the outside of the foundation with the airflow layer of theadditional ventilation panels vented at upper edges of the additionalventilation panels.